1. Field of the Invention
The present invention relates to inkjet printer heads used in image recording apparatuses.
2. Description of the Related Art
Inkjet printer heads functioning as liquid droplet jetting heads are used in image recording apparatuses such as printers, fax machines, and copiers, or in inkjet recording apparatuses used as image forming apparatuses. An inkjet printer head includes nozzles for jetting ink droplets, flow paths (liquid chambers) for communicating with the nozzles, and a pressure generating unit such as a piezoelectric element for generating pressure to be applied to the ink in the flow paths. Ink droplets are jetted from the nozzles by generating pressure with the pressure generating unit and applying the pressure to the ink in the liquid chambers.
In conventional inkjet printer heads, the respective liquid chambers and a common liquid chamber for communicating with the liquid chambers are made of materials such as photosensitive resin, resin mold, metal, and glass. However, liquid chambers made of resin have low rigidity, and therefore crosstalk is likely to occur between liquid chambers that are close to each other. Thus, good image quality may not be achieved. Meanwhile, liquid chambers made of metal and glass have high rigidity, but are difficult to fabricate. Thus, there may be difficulty in responding to demand for high density products to achieve high quality images.
There are proposals for forming liquid chambers and common liquid chambers by performing anisotropic etching on a silicon substrate (silicon wafer). Specifically, silicon flow path plates, which are used for forming liquid chambers, are fabricated as follows. On a silicon substrate (silicon wafer), liquid chambers and common liquid chambers corresponding to plural head chips are formed. Then, the silicon substrate (silicon wafer) is divided into plural flow path plates in accordance with the respective chips. If only a small number of flow path plates can be obtained from the silicon wafer (by dividing the silicon wafer), costs for fabricating flow path plates would increase.
In the inkjet recording heads disclosed in patent documents 1 to 4, the width of the flow path plate corresponds to the length between peripheral edges of the frame. Therefore, the width of the flow path plate cannot be reduced. In the inkjet recording heads disclosed in patent documents 5 to 8, a pressure attenuating mechanism (membrane, damper chamber) is disposed away from the common liquid chamber, and therefore the pressure attenuating mechanism has limited efficiency. Furthermore, in order to incorporate the mechanism in the recording head, the size of the recording head needs to be increased.
FIG. 2 is a cross-sectional side view of a conventional inkjet recording head. In the inkjet recording head, the outer walls of a frame 20, an oscillating plate 17, a flow path plate 10, and a nozzle plate 14 are aligned along the same plane (as indicated by each arrow on either side of the inkjet printer head). Thus, a width 33 of a common liquid chamber 30 and a margin to adhere 44 are wide, on either side of (left and right) the inkjet recording head. Accordingly, the flow path plate 10 has a wide width. Therefore, only a small number of flow path plates 10 can be obtained from a silicon wafer (by dividing silicon wafer). Consequently, high costs may be required for fabricating flow path plates.    Patent Document 1: Japanese Laid-Open Patent Application No. 2006-116767    Patent Document 2: Japanese Laid-Open Patent Application No. 2004-34293    Patent Document 3: Japanese Laid-Open Patent Application No. 2004-148813    Patent Document 4: Japanese Laid-Open Patent Application No. 2003-182076    Patent Document 5: Japanese Laid-Open Patent Application No. 2007-145014    Patent Document 6: Japanese Laid-Open Patent Application No. 2006-102980    Patent Document 7: Japanese Laid-Open Patent Application No. 2008-37099    Patent Document 8: Japanese Laid-Open Patent Application No. 2007-118312